By default Symplify automatically sync to all Google Analytics Streams found on your website. If you want to limit this you need to enter the Tracking ID/Measurement ID for the one(s) you want to sync with.
This is done in website settings. You can see this setting by clicking My websites -> click website -> Edit website -> Tracking -> Limit the Google Analytics Sync.
Here you enter the Tracking ID/Measurement ID for the ones you want us to sync with (whitelist). Multiple ID's are entered comma separated. Example: UA-XXXXXX-X, G-XXXXXXX, etc.
NOTICE: Measurement ID should not be mixed with Property ID. To find your Measurement ID in GA4 navigate to Admin -> Data Streams -> (Your websites Data Stream).